Invite friends to visit (and thus do not need to arrange a magnificent feast, because you can just meet for pizza or tea with cakes), prompted to choose somewhere all together (in a cafe, in a movie or on nature). Just do not think that one such meeting will be enough, try to turn them into a good tradition, and there friends begin to offer something different and interesting ideas for the pop group activities. And if you will communicate more, you will have more topics to talk about, shared memories and a desire to see again.
If between you and your friends "ran a black cat" and the relationship soured as a result of a quarrel, then we must act somewhat differently. No matter who is to blame for your disagreement, because if we talk frankly, to varying degrees, in a quarrel blame all - one for what fueled the conflict, while others - for the fact that he went to. Therefore, if the friendship road for you, and you want to establish a relationship, take the first step, even if you are convinced that the conflict is 100% to blame your friends. This does not mean that you should apologize and ask for forgiveness, we can just say that for you friendship and much more important than any quarrels and fights, and what you really want your relationship became unchanged. And if you were the instigator of conflict (even inadvertently), the sincere apologies little help smooth the situation. Perhaps, my friends did not immediately go to the world (if it is a really serious situations), but in any case you give them a reason to think. If the quarrel was trifling, after such a conversation with you, and it will be much easier to forget the insults and continue to be friends on.